Compressors are employed to increase the pressure of a gas in a variety of different applications and industries. Increasing the pressure of a gas through compression increases the temperature of the gas concurrently. Thus, in a single stage compressor, the temperature of a gas at the discharge of the compressor may be considerably greater than the temperature of the gas at the inlet of the compressor. For compressors including multiple stages, the second and following compressor stages require increasingly more work input per unit pressure increase on account of the elevated temperature of the gas handled by these later stages.
To address the elevated temperatures in multistage compressors, one approach pursued in the art has been the implementation of isothermal compression. Isothermal compression allows for a substantially constant temperature during the gas compression process, which, in turn, reduces the compression power needed. This may be accomplished by removing thermal energy, or heat, at the same rate that it is added by the mechanical work of compression. In practice, interstage coolers have been used to cool the gas between compressor stages. A common design employed in interstage coolers utilizes an external heat exchanger through which the gas is passed as it flows from a first compressor stage to a second compressor stage.
However, the use of interstage coolers typically increases the size and complexity of the compression system. Generally, interstage coolers require additional equipment, for example, heat exchangers and related piping, which may require additional space, especially in compression systems having multiple stages. Furthermore, such additional equipment adds additional expense and requires more frequent and extensive maintenance, resulting in a need for an increased budget for the building and maintenance of the compression system infrastructure.
What is needed, then, is an efficient, reliable, and compact cooling system for a compressor that is capable of transferring heat from the compressed gas to reduce the amount of work input required per unit pressure.